What was the immediate cause for the First World War?

The immediate event that led to the outbreak of the First World War took place on June 28, 1914. On that day, the Archduke Francis Ferdinand, heir to the Austrian throne, and his wife were shot dead by a young Serbian nationalist of the Black Hand at Sarajevo, the Bosnian capital. Following the assassination, the Austrian government declared war on Serbia on July 28, 1914.